Automobile bus systems are continuously developing toward higher bandwidths, lower latency periods, and stricter real-time capability. The CAN bus system has become widely accepted for the communication between sensors and control units. In the CAN bus system, messages are transmitted with the aid of the CAN protocol as it is described in the CAN specification in ISO 11898. Most recently, techniques have also been proposed in this regard, such as CAN-FD, in which messages are transmitted, and the like, in accordance with the specification “CAN with Flexible Data-Rate, Specification Version 1.0” (source http://www.semiconductors.bosch.de). Such techniques increase the maximally possible data rate through the use of higher clocking in the area of the data fields above a value of 1 Mbit/s.
In addition to primarily functional supplements, such as time-triggered CAN (TTCAN), the extension of the CAN standard most recently was extended with CAN-FD in particular with respect to the possible (higher) data rate and the usable data packet size, the quintessential CAN properties having been maintained, in particular in the form of the arbitration. Moreover, the signal representation in the data portion was essentially changed by a higher switching frequency of the signal states (high/low).
German patent document DE 10 2009 026 961 A1 discusses a method for transmitting data between user stations of a bus system, in which an extension of the existing CAN signal and of the associated communication device with respect to the use of high-frequency signals is disclosed, which are impressed onto the line in any arbitrary form (simultaneously or embedded) in relation to a CAN data stream. In particular, a coordination of the signal (synchronization signal, trigger) with the CAN signal is proposed.
At present, deliberations are being made to also enable higher speeds beyond CAN-FD, in particular in a range from 5 to 100 Mbit/s, for automobile bus systems. It should, however, also be possible to operate the user stations configured for higher speeds in mixed networks with existing CAN user stations or CAN nodes. It is problematic in this regard if this should necessitate an adaptation of the application software to the network having higher speeds in the CAN user stations of the bus system, since an adaptation of the application software is usually complex and therefore cost-intensive.